The subject matter disclosed herein relates to elevator systems. More specifically, the subject disclosure relates to brake systems to stop and hold elevator cars of an elevator system.
Elevator systems utilize ropes or belts operably connected to an elevator car, and routed over one or more sheaves, also known as pulleys, to propel the elevator car along a hoistway. The ropes or belts are driven by a machine, often an electric motor that rotates a drive sheave, raising or lowering the elevator car in the hoistway. The machine is often located at an upper end of the hoistway. When it is desired to stop motion of the elevator car, for example, to allow passengers to enter or exit the elevator car at a selected floor, or during an emergency, one or more electromagnetic brakes are applied, either at the machine or at the elevator car to stop and hold the elevator car.
For high rise, high speed, and/or high lift elevator systems, the typical electromagnetic brake requires a large number of calipers to adequately brake the system, resulting in increased complexity and potential failures of the braking system. Further, electromagnetic brakes calipers often noisily engage with the braking disk during operation, which is undesirable for passengers in the elevator car. Also, it is desired that the braking torque of the system be adjustable once installed to a desired braking torque to effectively stop the elevator car while preventing excessive deceleration and potential passenger injury therefrom. Finally, it is desired that braking systems be manually releasable to move the elevator car to a selected floor in the case of an emergency.